OpenGL examples

[Petr]

So here we have something interesting.

3D world using OpenGL. Since QB64PE already has _MouseMovement features fixed, it was really easy to add mouse movement.

The program requires files in the attachment in ZIP format. Freely available images are stored in it, which are used here as textures and, above all, the world.txt file. I have slightly modified it, so when you open it in the editor you will see the inscription NUMPOLLIES in it, it is important, followed by the number 36. This number indicates the number of triangles in the file, if you are going to make a modification, add three lines of numbers each time and increase the number 36 by 1!

Each line contains:

Vertex X, Vertex Y, Vertex Z for a 3D triangle, then X and Y for a 2D texture. My modification is that for every sixth line you can put the name of the image file in quotes after those numbers and it will then be used on the following triangle as wallpaper. That's why I write that you should put it on every sixth row, so that the texture is not different in each half of the square

The program has no collision detection, so you can walk through walls. I would probably solve the collision detection with an additional field where, when loading the triangle vertices in 2D, I would write down where the wall leads to, so that it really works, it is then necessary to shoot this 2D map in the same way as the image is shot during movement.

It can also be controlled from the keyboard with arrows and the Q and A buttons, or arrows + mouse, with the B button you can turn transparency on or off

Code: (Select All)

Declare CustomType Library
    Sub gluBuild2DMipmaps (BYVAL Target As _Unsigned Long, BYVAL iFormat As Long, BYVAL Wdth As Long, BYVAL Hght As Long, BYVAL format As _Unsigned Long, BYVAL typ As _Unsigned Long, BYVAL dat As _Offset)
End Declare


Type GL_Loader '                  array for loading textures
    PointerGL As Long
    TextureName As String
    Filtering As _Unsigned _Byte
End Type
ReDim Shared GLL(0) As GL_Loader, t As Long
Dim Shared GL_InitInfo As _Byte '  is need for OpenGL init
Dim Shared ExitSignal As _Byte '   is need for correct OpenGL exit when program end

'World3D coordinates array
Type Triangle
    TextureX As Single
    TextureY As Single
    VertexX As Single
    VertexY As Single
    VertexZ As Single
End Type

'World3D texture array
Type Texture_T
    FileName As String '                 texture file name
    Filter As _Byte '                    used texture filtering
    GL_Pointer As _Unsigned Long '       GL pointer (handle) for texture
End Type

ReDim Shared Triangles(0) As Triangle
ReDim Shared TriTextures(0) As Texture_T
Dim Shared Xpos, Zpos, Yrot, LookUpDown, WalkBias, Blend

_Title "World 3D"
LoadWorld "world.txt", Triangles(), TriTextures() 'just read TXT file and save coordinates to array Triangles and texture file names to  array TriTextures for us
'next step then is in _GL SUB - it call Init2 and there are all textures loaded to RAM

Const piover180 = 0.0174532925F 'the same function as _D2R  or  3.14/180
Screen _NewImage(1024, 768, 32)
Print "Welcome back in 2D world :)  Press Alt + F4 to end!"

_MouseHide
Do
    i& = _KeyHit
    While _MouseInput
        LookUpDown = LookUpDown + _MouseMovementY / 5 'Look up/down with mouse, angle is not locked!
        Heading = Heading - _MouseMovementX / 5: Yrot = Heading 'rotation left/right using mouse
$if win then 
      _MouseMove _Width / 2, _Height / 2 'lock mouse on the middle on the screen - causes problems in Linux
$end if
    Wend

    Select Case i&
        Case 20480 'arrow up
            Xpos = Xpos + Sin(Heading * piover180) * 0.05F
            Zpos = Zpos + Cos(Heading * piover180) * 0.05F
            If WalkBiasAngle >= 359.0F Then
                WalkBiasAngle = 0.0F
            Else
                WalkBiasAngle = WalkBiasAngle + 10
            End If
            WalkBias = Sin(WalkBiasAngle * piover180) / 20.0F



        Case 18432 'arrow down
            Xpos = Xpos - Sin(Heading * piover180) * 0.05F
            Zpos = Zpos - Cos(Heading * piover180) * 0.05F
            If WalkBiasAngle <= 1.0F Then
                WalkBiasAngle = 359.0F
            Else
                WalkBiasAngle = WalkBiasAngle - 10
            End If
            WalkBias = Sin(WalkBiasAngle * piover180) / 20.0F



        Case 19200 'arrow left
            Heading = Heading + 1
            Yrot = Heading
        Case 19712 'arrow right
            Heading = Heading - 1
            Yrot = Heading
        Case 81, 113 'Q - look up
            LookUpDown = LookUpDown - 1
        Case 65, 97 'A - look down
            LookUpDown = LookUpDown + 1
        Case 66, 98 'B
            Blend = Not Blend
    End Select '

    If ExitSignal Then System
    _Limit 50
Loop



Sub _GL ()

    Init2
    GL_Init

    _glClear _GL_COLOR_BUFFER_BIT And _GL_DEPTH_BUFFER_BIT 'Clear screen and depth buffer


    _glMatrixMode _GL_PROJECTION '                          Set projection matrix  - TRY comment this five rows and then run it. Black screen occur. For view just something then must be depth set to -1 (Z parameter in _glTranslateF)
    _glLoadIdentity ' Reset matrix
    _gluPerspective 45.0F, _Width / _Height, 0.1F, 100.0F ' Perspective calculation
    _glMatrixMode _GL_MODELVIEW '                           set modelview matrix

    texture = TriTextures(0).GL_Pointer


    Xtrans = -Xpos 'for walking in X axis
    Ztrans = -Zpos 'for walking in Z axis
    Ytrans = -WalkBias - 0.25F 'simulation steps
    SceneRotY = 360.0F - Yrot 'angle direction of view

    _glRotatef LookUpDown, 1.0F, 0.0F, 0.0F 'rotation i X axis - view up and down
    _glRotatef SceneRotY, 0.0F, 1.0F, 0.0F 'rotation in Y axis - rotation to left / right
    _glTranslatef Xtrans, Ytrans, Ztrans ' move to position (shift) in scene

    Triangles = UBound(Triangles) - 3 'total triangles used in txt file
    TriTextures_i = -1

    For L = 0 To Triangles Step 3 'step 3 - because triangle = 3 vertexes

        If L Mod 6 = 0 Then ' 6 is 6 vertexes for 2 triangle (1 quad)
            If TriTextures_i + 1 < UBound(TriTextures) Then 'if in texture array index is not UBOUND
                If TriTextures(TriTextures_i + 1).GL_Pointer > 0 Then 'if tritexture array  contains next valid texture
                    TriTextures_i = TriTextures_i + 1 '                increase index
                    texture = TriTextures(TriTextures_i).GL_Pointer ' insert next texture
                End If
            End If
        End If

        _glBindTexture _GL_TEXTURE_2D, texture 'tohle bude ve smycce vzdy po sesti bodech (6 bodu = 2 trojuhelniky)
        _glBegin _GL_TRIANGLES
        _glNormal3f 0.0F, 0.0F, 1.0F 'for light

        X_m = Triangles(L).VertexX
        Y_m = Triangles(L).VertexY
        Z_m = Triangles(L).VertexZ
        U_m = Triangles(L).TextureX
        V_m = Triangles(L).TextureY
        _glTexCoord2f U_m, V_m '     place texture first vertex
        _glVertex3f X_m, Y_m, Z_m '  place triangle first vertex

        X_m = Triangles(L + 1).VertexX
        Y_m = Triangles(L + 1).VertexY
        Z_m = Triangles(L + 1).VertexZ
        U_m = Triangles(L + 1).TextureX
        V_m = Triangles(L + 1).TextureY
        _glTexCoord2f U_m, V_m '     place texture second vertex
        _glVertex3f X_m, Y_m, Z_m '  place triangle second vertex

        X_m = Triangles(L + 2).VertexX
        Y_m = Triangles(L + 2).VertexY
        Z_m = Triangles(L + 2).VertexZ
        U_m = Triangles(L + 2).TextureX
        V_m = Triangles(L + 2).TextureY
        _glTexCoord2f U_m, V_m '     place texture third vertex
        _glVertex3f X_m, Y_m, Z_m '  place triangle third vertex
        _glEnd
    Next


    If _Exit Then
        '  DeleteTexture t 'if program end, first free texture from memory, then exit from GL and return to main loop
        KillAllTextures
        _glClear _GL_COLOR_BUFFER_BIT
        ExitSignal = Not 0
        Exit Sub
    End If

End Sub

Sub GL_Init
    If GL_InitInfo = 0 Then
        _glViewport 0, 0, _Width, _Height
        GL_InitInfo = 1
    End If
End Sub

Sub Init2
    _glEnable _GL_TEXTURE_2D 'allow texture maping
    _glBlendFunc _GL_SRC_ALPHA, _GL_ONE 'blending type for transparency
    _glClearColor 0.0, 0.0, 0.0, 0.5 'Black background
    _glClearDepth 1.0F '       depth buffer settings
    _glDepthFunc _GL_LESS '    depth testing type
    _glEnable _GL_DEPTH_TEST ' enable depth testing
    _glShadeModel _GL_SMOOTH 'allow smooth shading
    _glHint _GL_PERSPECTIVE_CORRECTION_HINT, _GL_NICEST ' best perspective projection

    If Blend Then
        _glEnable _GL_BLEND
    Else
        _glDisable _GL_BLEND
    End If


    If GL_InitInfo = 0 Then
        For L = 0 To UBound(TriTextures)
            If Len(TriTextures(L).FileName) Then t = LoadTexture(TriTextures(L).FileName, 1)
            TriTextures(L).GL_Pointer = t
            TriTextures(L).Filter = 1
        Next L
    End If
End Sub

Sub DeleteTexture (nr As Long)
    For P = LBound(GLL) To UBound(GLL)
        If GLL(P).PointerGL = nr Then
            Dim DEL As Long
            DEL = GLL(P).PointerGL
            _glDeleteTextures 1, _Offset(DEL)
            Exit Sub
        End If
    Next
End Sub

Sub KillAllTextures
    For P = LBound(GLL) To UBound(GLL)
        If GLL(P).PointerGL > 0 Then
            DeleteTexture P
            GLL(P).PointerGL = 0
        End If
    Next P
End Sub

Function LoadTexture (image As String, Filter As _Unsigned _Byte)
    If GL_InitInfo = 0 Then GL_Init
    If _FileExists(image) Then
        TT = 0
        Do Until TT = UBound(GLL)
            If GLL(TT).TextureName = image$ And GLL(TT).Filtering = Filter Then
                LoadTexture = GLL(TT).PointerGL 'prevent memory leak loading next and next texture again and angain...
                Exit Function
            End If
            TT = TT + 1
        Loop

        tex& = _LoadImage(image$, 32)
        _ClearColor _RGB32(255, 255, 0), tex&
        texinv& = _NewImage(_Width(tex&), _Height(tex&), 32)

        _PutImage (0, _Height(tex&))-(_Width(tex&), 0), tex&, texinv&

        ni& = _CopyImage(texinv&, 32) '_NewImage(32, 32, 32)

        Dim Texture As _Unsigned Long
        _glGenTextures 1, _Offset(Texture) 'generate our texture handle    (reserve place in memory for new texture)
        _glBindTexture _GL_TEXTURE_2D, Texture 'select our texture handle  (set this texture for use)

        Dim m As _MEM
        m = _MemImage(texinv&)

        Dim n As _MEM
        n = _MemImage(ni&)

        Select Case Filter
            Case -1
                'set our texture wrapping
                _glTexParameteri _GL_TEXTURE_2D, _GL_TEXTURE_WRAP_S, _GL_REPEAT
                _glTexParameteri _GL_TEXTURE_2D, _GL_TEXTURE_WRAP_T, _GL_REPEAT
            Case 0
                'set out texture filtering
                _glTexParameteri _GL_TEXTURE_2D, _GL_TEXTURE_MAG_FILTER, _GL_NEAREST 'for scaling up
                _glTexParameteri _GL_TEXTURE_2D, _GL_TEXTURE_MIN_FILTER, _GL_NEAREST 'for scaling down
            Case 1
                _glTexParameteri _GL_TEXTURE_2D, _GL_TEXTURE_MAG_FILTER, _GL_LINEAR 'for scaling up
                _glTexParameteri _GL_TEXTURE_2D, _GL_TEXTURE_MIN_FILTER, _GL_LINEAR 'for scaling down
            Case 2 'works....not sure, if this output is correct

                'gluBuild2DMipmaps(GL_TEXTURE_2D, pic->bpp/8, pic->width, pic->height, textureType, GL_UNSIGNED_BYTE, pic->data);


                gluBuild2DMipmaps _GL_TEXTURE_2D, 4, _Width(ni&), _Height(ni&), _GL_RGB, _GL_UNSIGNED_BYTE, _Offset(Texture)
                _glTexParameteri _GL_TEXTURE_2D, _GL_TEXTURE_MAG_FILTER, _GL_LINEAR_MIPMAP_NEAREST 'for scaling up
                _glTexParameteri _GL_TEXTURE_2D, _GL_TEXTURE_MIN_FILTER, _GL_LINEAR '  IF IS USED _GL_LINEAR_MIMAP_NEAREST here, program crash. Is it correct?    -?-
                '


                _glTexImage2D _GL_TEXTURE_2D, 0, _GL_RGB, _Width(ni&), _Height(ni&), 0, _GL_BGRA_EXT, _GL_UNSIGNED_BYTE, n.OFFSET

                _FreeImage tex&
                _MemFree n
                '_FreeImage ni&
                GoTo saveit

                'gluBuild2DMipmaps(GL_TEXTURE_2D, 3, TextureImage[0]->sizeX, TextureImage[0]->sizeY, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data);

        End Select

        _FreeImage tex&
        _glTexImage2D _GL_TEXTURE_2D, 0, _GL_RGB, _Width(texinv&), _Height(texinv&), 0, _GL_BGRA_EXT, _GL_UNSIGNED_BYTE, m.OFFSET

        saveit:
        U = UBound(GLL)
        GLL(U).PointerGL = Texture
        GLL(U).TextureName = image
        GLL(U).Filtering = Filter
        ReDim _Preserve GLL(U + 1) As GL_Loader

        _MemFree m

    Else
        Print "LoadTexture Error: "; image$; " - file not found."
    End If
    LoadTexture = Texture
End Function

Sub LoadWorld (txtFile As String, Triangles() As Triangle, TriTextures() As Texture_T)
    file$ = "world.txt"
    If _FileExists(file$) Then
        ReDim Num(4) As Single
        ff = FreeFile
        Open file$ For Input As ff
        While Not EOF(ff)
            radek = radek + 1
            Line Input #ff, t$
            t$ = t$ + " " '      add space to end line for right detection all numbers in the row
            i = InStr(1, t$, "NUMPOLLIES")
            If i Then
                Print "id: NUMPOLLIES  found"
                separator = InStr(i + 1, t$, " ")
                NumOfTriangles = Val(Mid$(t$, separator, Len(t$) - separator))
                Print "Triangles:"; NumOfTriangles
                ReDim Triangles(NumOfTriangles * 3) As Triangle
                ReDim TriTextures(NumOfTriangles) As Texture_T

                i = 0
                GoTo NextRow
            End If
            If InStr(1, t$, "/") = 0 Then 'row contains none C comment
                If Len(_Trim$(t$)) Then '  row is not empty
                    n$ = ""
                    For r = 1 To Len(t$)
                        ch = Asc(t$, r) '34 jsou uvozovky
                        Select Case ch
                            Case 48 To 57, 45, 46 '0 to 9 . -
                                num$ = num$ + Chr$(ch)
                            Case 32
                                If Len(num$) Then 'kdyz num$ obsahuje ciselnou hodnotu a dalsi znak je mezera
                                    '  Print num$
                                    ' Sleep
                                    Num(num_i) = Val(num$)
                                    num$ = ""
                                    If num_i = 4 Then
                                        num_i = 0 '0 to 4 for 5 number on 1 row
                                    Else
                                        num_i = num_i + 1
                                    End If
                                End If

                            Case 34 'narazil na uvozovky
                                next34 = InStr(r + 1, t$, Chr$(34))
                                ' Print r, next34
                                TextureName$ = Mid$(t$, r + 1, next34 - r - 1) 'vraci jmeno textury bez uvozovek
                                Exit For
                        End Select
                    Next r 'loop for 1 row

                    Triangles(Tri_i).TextureX = Num(3) 'records in text file:  Xvertex, Yvertex, Zvertex, TextureX, TextureY, "texturefilename" (if is changed)
                    Triangles(Tri_i).TextureY = Num(4)
                    Triangles(Tri_i).VertexX = Num(0)
                    Triangles(Tri_i).VertexY = Num(1)
                    Triangles(Tri_i).VertexZ = Num(2)
                    Tri_i = Tri_i + 1
                    'Print radek, Tri_i
                    'Sleep
                    If Len(TextureName$) Then
                        ' Print TextureName$
                        TriTextures(TriTex_i).FileName = TextureName$
                        TriTex_i = TriTex_i + 1
                        TextureName$ = ""
                    End If
                    ReDim Num(4) As Single 'clear array for read next values
                Else
                    GoTo NextRow 'if row is empty, read next row from file
                End If
            Else
                GoTo NextRow ' if row contains C comment separated with // (or just /), read next row from file
            End If
            NextRow:
        Wend
    Else
        Print "File world.txt not found.": End
    End If
    Close ff
End Sub